[R-sig-Geo] plot.Map deprecated, alternative ?

[Markus Loecher]

Dear all, 
I understand that plot.Map (the default method for plotting shape objects) is deprecated, however I have not found a working method converting my shape file into either a polylist or sp class.
I tried the following 
   p2roads <- read.shape("sf.shp")
  SF.map <- Map2poly(p2roads)
where sf.shp is a shape object of the San Francisco street map, and get the following error message:
   Error in Map2poly(p2roads) : maptype not poly
Are there differences between shape files ? Which other way could I try to convert my shape object so that plot.Spatial will work ?

Thanks !

Markus